This invention relates to a radial piston hydraulic motor with variable eccentricity.
Hydraulic motors having a number of cylinder-piston units arranged radially about a cam or eccentric which is attached to the motor rotating shaft are known in the art.
Propulsive power is transmitted to the cam by means of a working fluid being pressurized by a specially provided pump and cyclically distributed to the various cylinder-piston units by a distributor.
In order to change the motor power output, the pump operation is controlled to variously set the working fluid flow rate and pressure. However, this requires the availability of a pump which can be adapted to different operating conditions of the motor, and accordingly, a large size one.
It has also been proposed to vary the motor eccentricity so as to change its swept volume and, hence, the torque transmitted to the rotating shaft and the rotational speed, while keeping the pump delivery rate constant.